There are known transparent or semitransparent sheets having patterns printed on both of their front and back surfaces (see, for example, JP 2009-128734 A). When the sheet described in JP 2009-128734 A is receiving light from a front-surface side, with no light from a light source disposed on a back-surface side, it is mostly the pattern printed on the front surface of this sheet that is visually recognized from the front-surface side. On the other hand, when this sheet is being exposed to light radiated from the light source on the back-surface side, with light coming from the front-surface side being substantially blocked, the pattern printed on the back surface may be visible from the front-surface side under light radiated from the light source. Then, the pattern may be more easily caught by the eye from the front side than when observed without light from the light source on the back-surface side.
In the sheet described in JP 2009-128734 A irradiated with light from the front-surface side, the pattern printed on the back surface may possibly be caught by the eye from the front-surface side, even without any light from the light source on the back-surface side. To address this identified issue of the known art, a multilayered printed matter including a plurality of print layers formed on a medium; two pattern layers having patterns printed thereon, and concealing layers formed between the two pattern layers so as to conceal the pattern on one of the pattern layers not to affect the pattern on the other pattern layer.
The multilayered printed matter includes, for example, a medium 102 such as an acrylic board, and four print layers 103 to 106 formed on the medium 102, as illustrated in FIG. 8. The print layers 106, 105, 104, and 103 are stacked on one another upward in the mentioned order on a surface of the medium 102. The print layers 103 to 106 are formed one by one by ejecting and curing UV-curable inks. The print layers 103 and 106 are pattern layers, and the print layers 104 and 105 are concealing layers. Thus, this printed matter has a two-layered concealing structure.
In this multilayered printed matter, the print layer 106 printed on one surface of the medium 102, which is a pattern layer, may have a part(s) lacking effective pixels and/or a thinner part(s) printed at a lower concentration. Then, a recessed part 106a recessed into a surface of the print layer 106 toward the medium 102 may be formed in part of the print layer 106 lacking effective pixels or printed at a lower concentration. The recessed part 106a may be filled with ink in part of the print layer 105. As a result of the recessed part 106a being filled with ink in part of the print layer 105, a recessed part 105a recessed into a surface of the print layer 105 toward the medium 102 may be formed in the print layer 105. The recessed part 105a may be filled with ink in part of the print layer 104. As a result of the recessed part 105a being filled with ink in part of the print layer 104, a recessed part 104a recessed into a surface of the print layer 104 toward the medium 102 may be formed in the print layer 104. The recessed part 104a may be filled with ink in part of the print layer 103.
As a result of the recessed part 104a being filled with ink in part of the print layer 103, a recessed part 103a recessed into a surface of the print layer 103 toward the medium 102 may be formed at a position(s) irrelevant to a pattern printed on the print layer 103. In case the recessed part 103a is formed at a position(s) irrelevant to a pattern printed on the print layer 103 on the surface of the print layer 103 constituting an outermost surface of the multilayered printed matter, the printed matter may look less attractive and degrade in visual quality. Thus, an issue identified with such a multilayered printed matter that includes, as the print layers, two pattern layers and concealing layers formed between the pattern layers, is that multilayered printed matters thus structured may be likely to degrade in appearance and visual quality.
In some multilayered printed matters, the print layer 105, which is part of the concealing layers, may lack effective pixels and accordingly have a recessed part(s). In that case, a recessed part(s) recessed into the surface of the print layer 103 toward the medium 102 may be formed at a position(s) on the print layer 103 irrelevant to the pattern printed thereon. Then, the obtained multilayered printed matter may likewise degrade in appearance and visual quality.